Braun tube



B. WIENECKE BRAUN' TUBE Filed June 5, 1933 If? van for": fimzw Mi Patented Oct. 26, 1937 UNITED STATES PATENT rice BRAUN TUBE Application June 3, 1933, Serial No. 674,204 In Germany June 8, 1932 8 Claims.

It has been found that, particularly when employing high-emission cathodes of the metallic vapour type, it is necessary to outgas the parts of the system very carefully, preferably before application of the emissive coating.

The subject matter of the invention is a Braun tube, the system of which is constructed and arranged in such fashion that all parts of the system are outgassed, possibly wholly independently of each other, and the application of the metal by atomization may be performed after completion of the outgassing process. At the same time the system comprising cathode, Wehnelt cylinder and anode is constructed, in

accordance with the invention, in such fashion that centering upon the assembly takes place automatically. For this purpose all parts of the system-insofar as the same are not held together by direct attachmentare guided on or secured to common guide members or the like. The individual parts of the system are furnished With a cross-section, the form and size of which is such that they contain a magnetic flux adequate for heating to the outgassing temperature.

Those parts, the cross-section of which is relatively small, so that the same alone cannot be raised to the requisite temperature without overheating of the adjacent parts of larger crosssection, are secured, in accordance with the in- 3 vention, to auxiliary plates, which may be raised readily to a high temperature by eddy current heating, and at the same time, by the conduction of heat, assist considerably towards heating of the parts of smaller cross-section. The systern, in accordance with the invention, is constructed as a pot system closed off completely towards the rear and th sides, so that spreading effects are unable to take place. The high-emission metal to be atomized in accordance with the invention, atomized by directed evaporation, so that the same strikes in the main against the cathode. By reason of the particular form of the system the formation of conductive layers of the atomized metal outside of the system is completely avoided.

In the drawing a form of embodiment of the tube according to the invention, and also certain details, are shown by way of example, in part diagrammatically.

Fig. 1 shows the complete arrangement,

while in 1 Fig. 2 there is shown the system comprising cathode, Wehnelt cylinder and anode, in

Fig. 3 the cathode of the system, in

Fig. 4 the pair of deflecting plates, and in Fig. 5 the insulating holding means for the high-potential anode. I

In the drawing 1 is the bulb of the Braun tube having the pinch 28, to which there may be secured the holding means 2 for the pairs of de- 5 fleeting plates l and 5, for example by means of the band 28. Naturally it is also possible, particularly when employing a pinch having a very large surface, to fuse the holding means 2 into the pinch itself. In this case the holding means 10 may consist of a stable metal tube having a relatively large thickness of wall and small diameter, fused into the pinch, and of the actual holding portion, which may be connected with the fusedin holding tube .by introducing it into or slipping 15 it over the same or by welding. The actual system producing the cathode ray consists of the Wehnelt cylinders I ll, I I, with the cathode I1, the screening anode I8 and the high-potential anode 2!. The Wehnelt cylinder in accordance with the invention may consist of a cylinder of relatively small diameter Ill, which is connected with a plate 9 of larger diameter and, by means of the intermediate cover H, with the cylinder ll of larger diameter. The cathode |las shown 25 more particularly by Fig. 3-is introduced into a metallic part !4 by means of an insulating tube. The part i l may naturally be constructed as a massive cylinder. It has been found convenient, however, to construct the samein order to diminish its heat capacity as far as possiblefor example in the form shown. The cathode I! is finally mounted with its leads l5, It in the part l4, and the part M is then simply introduced into the cylinder H3. The holding plate 9 of the sys- 35 tem is guided, for example, by borings, preferably on three metallic holding devices 3, which are fused into the pinch either in direct fashion, or preferablyfor increasing the stabilitywith the inclusion of transverse members. The 40 Wehnelt cylinder H is closed off at the front by the mica disc 2t, which is furnished with an aperture of relatively small diameter, and on the inner side of which there is arranged the screening anode 58. At a relatively slight distance ,5 from the insulating disc 20 there is arranged the main anode 2| with the current lead 22 and the lead 23. The mica disc 20 in the same manner as the high-potential anode 2i and the systemsupporting plate 9 is secured to the holding 50 means 3. The supply of potential to the Wehnelt cylinder takes place via the holding means 3, and the supply of potential to the screening anode l8 over a lead not shown in the drawing and insulated against the Wehnelt cylinder by means 55 of the mica disc 20. In order to screen off the interior of the Wehnelt cylinder as completely as possible against the field of the high-potential anode the diameter of the screening anode l8 must be as large as possible. The same is preferably so dimensioned that the distance between the wall of the Wehnelt cylinder and the screen ing anode amounts to 1 mm. or less. Were the screening anode to rest immediately against the mica disc 29, conductive bridges would be able to form between the anode and the Wehnelt cylinder on the sheet of mica upon the atomization of the light metal provided in the capsule l2 with the tube fitting I3. To ensure that the possibility of a conductive connection of this nature between the screening anode and the Wehnelt cylinder is precluded, there may be provided, in accordance with the invention, between the screening anode l8 and the mica plate 20 a distance disc [9, which preferably possesses a considerably smaller diameter than the anode i8. Naturally this distance plate may consist equally well of insulating material or metal. It has been found convenient, however, to make the two discs I8 and E9 of the same metal. The highpotential anode 2| requires to be insulated electrically against the holding means 3.

The assembly of the system may be performed in the following manner. At first the cathode portion I4 with the completely mounted cathode I! is introduced into the cylinder l0 connected with the disc 9, and the disc 9 fitted over the holding means 3 and secured to the same, for example by welding. There is then fitted the intermediate cover 21, and on the latter the cylinder ll. Naturally the cylinder ll and/or the cover 21 may also be furnished with abutments which are likewise guided on the holding means 3. The insulating plate 20, which is also guided on the holding means 3 and to the inner side of which there is secured the anode I8. with the intermediate member l9, is thereupon fitted. Over the holding means 3 there are then slipped insulating tubes 26 (Fig. 5). On the insulating tubes 26 there are fitted insulating tubes 24, and then the anode slipped over, the insulating tubes 24 fitted on, and the whole secured in immovable fashion with the assistance of the plug 25, since all parts are secured to the same holding means 3, centering takes place automatically. It has been found that upon the assembly according to the invention subsequent centering is unnecessary.

The cathode may preferably be constructed as an indirectly heated, pointed cathode (preferably: barium oxide-barium cathode). It has been found that for proper working of the tube it is important to dimension correctly the spacing between the cathode and the cylinders l0 and II. The distance of the cathode point from the edge surface of the cylinder 10 should preferably amount to approximately 1-3 mm., and the distance from the surface of the cylinder edge I l to approximately 3l0 mm., assumed the potential of the cylinder is 100- -300 and the potential of the screening anode i8 approximately +100-+500 volts.

As shown more particularly by Fig. 2, the metal to be atomized is arranged in a capsule l2, which is connected with the interior of the cylinder by the tube I3, and may be raised by eddy current heating to the temperature necessary for atomization of the metal independently of the other parts of the system.

As shown in Fig. 4, the deflecting plates 4 and 5 are preferably given such a form that they may be raised alone by eddy current to the outgassing temperature. In this connection semi-cylindrical form has been found particularly convenient. In order to avoid safely distortion of the plates during the outgassing heating process, it is necessary to employ relaxed material. The deflecting plates 4 may conveniently be secured to a circular holding device 6, which in turn is attached to holding means 2. The one plate is in conductive connection with the holding means 2 (which may be maintained at anode potential), whilst the second plate, to which there is conducted the control potential over the line '8, is insulated against the holding means by the insulating plate 1.

Naturally it is quite readily possible to modify details of the arrangement. In particular it is possible to secure also the deflecting plates to the same holding means as the system producing the cathode ray, so that the centering of the deflecting plates in relation to the system also takes place automatically upon the assembly.

If the tube according to the invention is to be employed more particularly for television purposes as tube with light control, the screening anode may be used as control electrode. Naturally, however, it is also possible in this case to provide a special control grid within the dark space of the cathode, which grid if necessary may be screened oif against the Wehnelt cylinder by a screening grid raised to a suitable potential.

In place of a pointed cathode it is naturally also possible to employ any other desired cathodes, such, for example, as cathodes with meandrian emissive surface and the like. It is furthermore possible, in place of barium oxide-barium cathodes, which are produced preferably by atomizing barium on to a smeared oxide cathode, also to employ cathodes which may be produced by atomizing barium or another light metal on to a tungsten dioxide base. The essential feature in each case is that the arrangement of the single parts is such that the application to the cathode by atomization may be performed after the outgassing of the system.

I claim:

1. A Braun tub-e comprising a press, an envelope sealed to said press, a plurality of rodshaped supporting members secured to said press and extending in a direction parallel to the axis of said tube, a cathode, an assembly of electrodes comprising a plurality of cylinder-shaped members disposed co-axially with said tube and a plurality of apertured plate anodes disposed perpendicular to the axis of said tube, a plurality of supporting plates having guiding holes corresponding in number and situation to said supporting members, each of said supporting plates being attached to an electrode of said assembly, said supporting members projecting through said guiding holes and locating the electrodes of said assembiy in position, and deflecting means supported from said press.

2. A Braun tube comprising a press, an envelope sealed to said press, a plurality of rodshaped supporting members secured to said press and extending in a direction parallel to the axis of said tube, an assembly of electrodes comprising a plurality of cylinder-shaped members disposed co-axially with said tube, a cathode, and a plurality of apertured plate anodes disposed perpendicular to the axis of said tube, a metallic cathode holder locating said cathode in position with respect to one of said cylinder-shaped members and inside thereof and being insulated from said cathode, a plurality of supporting plates having guiding holes corresponding in number and situation to said supporting members, each of said supporting plates being attached to an electrode of said assembly, said supporting members projecting through said guiding holes and locating the electrodes of said assembly in position, and deflecting means supported from said press.

3. The invention set forth in claim 1, and wherein said assembly of electrodes comprises an anode which is provided, in the same manner as said supporting plates, with guiding holes corresponding in number and situation to said supporting members, said supporting members projecting also through said guiding holes in said anode and locating said anode in position relatively to the remaining parts of said assembly.

4.. A Braun tube including a Wehnelt cylinder including at least one hollow cylindrical portion, a metallic cathode holder mounted inside said Wehnelt cylinder and having at least one cylindrical portion, the outer diameter of which is equal to the inner diameter of said hollow cylindrical portion, said second mentioned cylindrical portion having its outer surface located adjacent to the inner surface of said hollow cylindrical portion for axially aligning said cathode holder with said Wehnelt cylinder, and a thermionic cathode supported and positioned in said Wehnelt cylinder by and insulated from said cathode holder, said cathode having an emissive surface located symmetrically in relation to the axis of said second mentioned cylindrical portion.

5. A Braun tube comprising a press, an envelope sealed to said press, a fluorescent screen, a Wehnelt cylinder including at least one hollow cylindrical portion, a metallic cathode holder mounted inside said Wehnelt cylinder and having at least one cylindrical portion the outer diameter of which is equal to the inner diameter of said hollow cylindrical portion, said second mentioned cylindrical portion having its outer surface located adjacent to the inner surface of said hollow cylindrical portion for axially aligning said cathode holder with said Wehnelt cylinder, and a thermionic cathode supported and positioned in said Wehnelt cylinder by and insulated from said cathode holder, said cathode having an emissive surface located symmetrically in relation to the axis of said second mentioned cylindrical portion, at least one anode mounted in operative relationship to said cathode, two pairs of deflecting plates mounted between said anode and said screen, and a plurality of metallic holders attached to said press, said metallic holders supporting said Wehnelt cylinder having said cathode positioned therein by means of said cathode holder and all of the other said electrodes.

6. A Braun tube including a Wehnelt cylinder including at least one hollow cylindrical portion, a metallic cathode holder mounted inside said Wehnelt cylinder and having at least one cylindrical portion the outer diameter of which is equal said second mentioned cylindrical portion, and a metallic holding plate attached to said Wehnelt cylinder, said holding plate having a plurality of guiding holes.

7. A Braun tube including aWehnelt cylinder including at least one hollow cylindrical portion, a metallic cathode holder mounted inside said Wehnelt cylinder and having at least one cylindrical portion the outer diameter of which is equal tothe inner diameter of said hollow cylindrical portion, said second mentioned cylindrical portion having its outer surface located adjacent to the inner surface of said hollow cylindrical portion for axially aligning said cathode holder with said Wehnelt cylinder, and a thermionic cathode supported and positioned in. said Wehnelt cylinder by and insulated from said cathode holder said cathode having an emissive surface located symmetrically in relation to the axis of said second mentioned cylindrical portion, a metallic holding plate attached to said Wehnelt cylinder, said holding plate having a plurality of guiding holes, and a container containing a vaporizable metal, said container being attached to said Wehnelt cylinder by means of a short metal tube, the inner space of said container communicating with the inner space of said cylinder through said metallic tube.

8. A Braun tube comprising a press, an envelope sealed to said press, a plurality of metallic holders attached to said press, a Wehnelt cylinder including at least one hollow cylindrical portion, a metallic cathode holder mounted inside said Wehnelt cylinder and having at least one cylindrical portion the outer diameter of which is equal to the inner diameter of said hollow cylindrical portion, said second mentioned cylindrical portion having its outer surface located adjacent to the inner surface of said hollow cylindrical portion for axially aligning said cathode holder with said Wehnelt cylinder, and a thermionic cathode supported and positioned in said Wehnelt cylinder by and insulated from said cathode holder, said cathode having an emissive surface located symmetrically in relation to said second mentioned cylindrical portion, and a metallic holding. plate attached to said Wehnelt cylinder, said holding plate having a plurality of guiding holes, said Wehnelt cylinder being slipped over said metallic holders with the use of said guiding holes of said supporting plate, at least one anode arranged in operative relationship to said cathode, a fluorescent screen, and two pairs of deflecting plates, said anode and said deflecting plates being attached to said metallic holders.

BRUNO WIENECKE. 

